Fuel Injector Filter

Abstract

A filter for a control flow of a fuel injector, wherein a primary fuel flow enters the injector through an inlet aperture, and wherein part of the primary fuel flow forms a secondary fuel flow which enters a control valve through a control flow aperture, wherein the filter is located such that only the secondary flow of fuel passes through the filter, the filter includes filter orifices such as slots, holes or perforations, wherein at least one dimension of the filter orifices is less than the nozzle control valve lift value.

1 - 9 . (canceled) 
     
     
         10 . A fuel injector for use in delivering fuel in an internal combustion engine, the fuel injector comprising:
 a housing;   an inlet aperture;   a control flow aperture leading to a nozzle control valve having a known lift value;   a needle piston;   a nozzle cavity provided with at least one nozzle outlet opening, wherein a primary fuel flow enters the injector through the inlet aperture, and wherein part of the primary fuel flow forms a secondary fuel flow which enters the nozzle control valve through the control flow aperture, and wherein the nozzle control valve controls movement of the needle piston, thereby controlling flow of fuel out of the nozzle cavity through the at least one nozzle outlet opening; and   a filter located such that only the secondary flow of fuel passes through the filter, the filter comprising at least one filter orifice, wherein at least one dimension of the at least one filter orifice is less than the known lift value of the nozzle control valve.   
     
     
         11 . A fuel injector as claimed in  claim 10  wherein the filter is located in a fuel flow path between the inlet aperture and the nozzle cavity such that the primary fuel flow passes over an upstream surface of the filter. 
     
     
         12 . A fuel injector as claimed in  claim 10  wherein the at least one dimension of the at least one filter orifice is between a half and a quarter of the known lift value of the nozzle control valve. 
     
     
         13 . A fuel injector as claimed in  claim 10  wherein the at least one filter orifice comprises a plurality of slots, wherein the at least one dimension of the slots is a width of each slot. 
     
     
         14 . A fuel injector as claimed in  claim 10  wherein the at least one filter orifice comprises a plurality of holes or perforations wherein the at least one dimension is a maximum diameter of each hole or perforation. 
     
     
         15 . A fuel injector as claimed in  claim 10  wherein the filter is mounted in the injector housing and comprises a tube, and wherein the at least one filter orifice is provided on a surface of the tube. 
     
     
         16 . A fuel injector as claimed in  claim 10  wherein the at least one filter orifice is provided on a surface of a component or part of the injector. 
     
     
         17 . A fuel injector as claimed in  claim 10  wherein the at least one filter orifice comprises a clearance between two components and wherein the at least one dimension of the at least one filter orifice is the clearance between the two components. 
     
     
         18 . A fuel injector as claimed in  claim 10  wherein the at least one filter orifice comprises a mesh comprising a plurality of mesh orifices and wherein the at least one dimension of the filter orifice is a minimum dimension of each mesh orifice.